Chapter 20: Origin of Life on Théxar

"In the beginning was not Light. In the beginning was Matter that learned to remember itself. We are not a creation. We are a continuation. Memory become flesh." — From the "Book of Origin," canonical text of Xha'Ruun, Era of Unity

Related sections: → see [Ch.04, "Biochemistry"], → see [Ch.12, "Geological Evolution"], → see [Ch.05, "Species Xha'Ruun"] Key principle: life on Théxar arose during the early history of the planet in H₂S-rich hydrothermal vents of the Gharra ocean. The key difference — a 6-letter genetic code, which emerged as an adaptation to elevated cosmic radiation.

Introduction

The origin of life on Théxar is one of the fundamental chapters of the encyclopedia. It connects the planet's geological history (Ch.12) with biochemistry (Ch.04) and the evolution of species (Ch.05, Ch.18).

Abiogenesis involved several chemical transitions: synthesis and concentration of organic molecules, polymer formation, and enclosure in self-maintaining protocells.

20.1 Conditions for the Emergence of Life

20.1.1 Chemical Environment of Early Théxar

In its early history, Théxar was a world radically different from today:

20.1.2 Site of Abiogenesis

The main "reactor" of prebiotic chemistry became the hydrothermal vents of the Gharra ocean, where four key conditions were met:

1. Temperature gradient — from 235.4°X (vent) to 47.3°X (surrounding water)
2. pH gradient — from acidic (vent, pH 4–5) to slightly acidic (ocean, pH 6.5)
3. Catalytic surfaces — pyrite (FeS₂), clay, silicon sediments
4. Constant energy supply — chemical (H₂S, H₂, CH₄) and thermal

Fig. 20.1. Hydrothermal vent as a prebiotic reactor.

20.2 Prebiotic Chemistry

20.2.1 Abiogenic Synthesis of Organics

Experimental data (reproduced by Xha'Ruun civilization in laboratory conditions) support the following possible path of abiogenesis:

Stage 1: Formation of "soups" In the atmosphere of early Théxar (CO₂+N₂+H₂S) under the action of UV radiation and lightning discharges, the following were synthesized:

• Formaldehyde (CH₂O)
• Hydrogen cyanide (HCN)
• Hydrogen sulfide (H₂S)
• Thioacetate (CH₃COSH — key for sulfur metabolism)

Stage 2: Concentration Hydrothermal cycles and evaporation in tidal zones concentrated organics in porous silicon matrices.

Stage 3: First polymers On the surface of pyrite (FeS₂) and clay minerals, polymerization occurred:

• Amino acids → peptides
• Nucleotides → RNA
• Silicic acids → polysiloxanes

20.2.2 The 6-Letter Code Hypothesis

The emergence of the 6-letter genetic code is the key puzzle of Théxar's abiogenesis. The dominant theory is the radiation protection hypothesis:

1. High UV flux of early Théxar caused frequent mutations in short RNA-like chains
2. Additional bases (P — pyrimidine-N, X — xanthosine) increased chain stability and provided coding redundancy
3. The six-letter code gave 6³ = 216 codons (versus 4³ = 64 for a four-letter code), which allowed:
   • Encoding 24 amino acids (versus 20)
   • Having ~9× redundancy (versus 3×)
   • 5× higher mutation resistance

KEY FACT

The six-letter code is explained in this hypothesis as a possible evolutionary response to radiation pressure. Laboratory experiments by Xha'Ruun showed that under UV irradiation, the tested four-letter RNA analogues degraded 5× faster than the tested six-letter analogues under the experimental conditions. At the radiation background of early Théxar (3.5× higher than modern), 6-letter systems had a decisive advantage.

20.3 From Chemistry to Life

20.3.1 Protocells

The first protocells formed in the hydrothermal vents of Gharra. Their key features:

• Membrane: silicon-carbon lipids (Si-C), more stable at high T than phospholipids
• Metabolism: chemoautotrophic (Fe-S → FeS₂ + H₂ → energy)
• Genetics: RNA world with 6-letter code
• Reproduction: division (without sexual process)

20.3.2 First Cells

The emergence of the first true cells (prokaryotes) marked the beginning of biogeochemical cycles:

20.3.3 Oxygen Catastrophe

KEY FACT

Oxygen began to accumulate after oxygen-producing photosynthesis evolved. At first it oxidised dissolved iron and other reduced substances; later it changed the atmosphere. Anaerobic communities persisted in oxygen-free refuges.

Consequences:

1. Mass extinction of anaerobic forms (survived only in deep-water and underground refugia)
2. Oxidation of dissolved Fe²⁺ in the oceans → formation of banded iron formations (BIF)
3. Formation of the ozone layer
4. Evolution of aerobic metabolism

20.4 Chronology of Evolution

Chapter Summary

Key conclusions:

1. Life on Théxar arose during the early history of the planet in H₂S-rich hydrothermal vents of the Gharra ocean.
2. The 6-letter genetic code — adaptation to elevated UV radiation of early Théxar.
3. Oxygen-producing photosynthesis transformed the oceans and atmosphere.
4. The dominant class — Thermochromadae, which appeared ~350 million cycles ago.
5. The emergence of Xha’Ruun preceded their documented settlements and writing.
6. The six-letter code provides greater coding redundancy.
7. Cambrian radiation on Théxar occurred ~350 million cycles ago.

Connections to other chapters:

• → see [Ch.04, "Biochemistry"] — 6-letter code, alternative chirality
• → see [Ch.12, "Geological Evolution"] — conditions of early Théxar
• → see [Ch.15, "Atmosphere"] — atmospheric composition during abiogenesis
• → see [Ch.18, "Fauna"] — evolution of Thermochromadae
• → see [Ch.05, "Species Xha'Ruun"] — evolution of Xha'ri